Triboelectric nanogenerator based on electrodeposited Ag octahedral nano-assemblies

The tremendous potential of triboelectric generators-TENGs for converting mechanical energy into electrical energy places them as one of the most promising energy harvesting technologies. In this work, the fabrication of enhanced performance TENGs using Ag octahedron nano-assemblies on ITO as electrodes significantly increases the electric charge collection of the induced tribocharges. Thereby, nanostructured electrical contacts coated with Ag macroscale nano-assemblies with octahedral features were obtained by the electrodeposition technique on flexible PET/ITO substrates. Consequently, the nanostructured triboelectric generator-TENG exhibited 65 times more maximum output power, and almost 10 times more open circuit output voltage than that of a TENG with non-nanostructured contacts passing from μW to m W capabilities, which was attributed to the increment of intrinsic interface states due to a higher effective contact area in the former. Likewise, output performances of TENGs also displayed an asymptotic behavior on the output voltage as the operating frequency of the mechanical oscillations increased, which is attributed to a decrement in the internal impedance of the device with frequency. Furthermore, it is shown that the resulting electrical output power can successfully drive low power consumption electronic devices. On that account, the present research establishes a promising platform which contributes in an original way to the development of the TENGs technology.

Lignin in storage and renewable energy applications： A review

Lignin is a cheap, abundant and non-toxic group of complex phenolic polymers obtained in large amounts from the papermaking and cellulosic biofuel industries. Although the application of lignin has been ex- plored in these and several more industries, there are limited applications of lignin in the energy industry. However, numerous research revealed a great interest in the exploration of this renewable biopolymer in storage energy devices. Some of these applications include the use of lignin as an expander for lead-acid batteries, electrodes for primary and rechargeable batteries, electrodes for electronic double layer capac- itors and electrochemical pseudocapacitors, and to feed different types of fuel cells. The use of lignin in energy storage devices improves not only the performance of these devices but also decreases the price and toxicity, contributing to obtaining greener energy devices. Based on the above, this review provides an overview of the main research work related to the use of lignin as a renewable component, suitable to replace some synthetic and toxic compounds used in the fabrication of energy storage devices with particular emphasis on batteries, advanced supercapacitors, and solar and fuel cells.

Method for Signals Detection in Single Crystal Diffraction Patterns through a Diffraction Pattern Indexing Software

The correct use of information in science and technology is very important for its progress. Nowadays, the equipment used for the scientific and technological development provides results that are later interpreted by the researchers, in most of the above mentioned equipment the results are images full of information which has to be analyzed. A powerful stage with multiple benefits in this field is the image pre-processing by means of intelligent systems, which are capable to do image analysis throwing very useful results that enhance the scientific and technological information. There are currently more than 500 functions in the computational vision specialized open source library OpenCV, which associated with the C＋＋ programming language. These functions are used for application development in many areas of computer vision such as products inspection, medical images, safety, user＇s interfaces, camera calibration, stereoscopic vision and robotics. In this development and research work, by using the available functions and modifying the exposed methods, we present a proposal for signal detection in images originated in the transmission electron microscope （known as diffraction patterns）, which are attached to the detailed analysis of crystalline structures used in the study of the materials science, the results show a profit of at least 18% in the detection of signs by means of the method proposed in this work.

Sub-10nm nanogap fabrication on suspended glassy carbon nanofibers

Glassy carbon nanofibers(GCNFs)are considered promising candidates for the fabrication of nanosensors for biosensing applications.Importantly,in part due to their great stability,carbon electrodes with sub-10 nm nanogaps represent an attractive platform for probing the electrical characteristics of molecules.The fabrication of sub-10 nm nanogap electrodes in these GCNFs,which is achieved by electrically stimulating the fibers until they break,was previously found to require fibers shorter than 2µm;however,this process is generally hampered by the limitations inherent to photolithographic methods.In this work,to obtain nanogaps on the order of 10 nm without the need for sub-2µm GCNFs,we employed a fabrication strategy in which the fibers were gradually thinned down by continuously monitoring the changes in the electrical resistance of the fiber and adjusting the applied voltage accordingly.To further reduce the nanogap size,we studied the mechanism behind the thinning and eventual breakdown of the suspended GCNFs by controlling the environmental conditions and pressure during the experiment.Following this approach,which includes performing the experiments in a high-vacuum chamber after a series of carbon dioxide(CO 2)purging cycles,nanogaps on the order of 10nm were produced in suspended GCNFs 52µm in length,much longer than the~2µm GCNFs needed to produce such small gaps without the procedure employed in this work.Furthermore,the electrodes showed no apparent change in their shape or nanogap width after being stored at room temperature for approximately 6 months.

Characterization of Topsoil Samples and Analysis of the Distribution of Heavy Metals in Parral Chihuahua, Mexico

During the 17th Century, Parral City in the Chihuahua State in Mexico was one of the most important miner zones in the whole world. After more than three centuries important amounts of residuals, known as tailings, with high contents of heavy metals were generated. These residuals are a potential risk for the environment and human health. Given to that, it decided to carry out the analysis of the concentrations of cadmium, lead, chromium, zinc and arsenics, in topsoil samples susceptible of airborne transport and accumulation in risky zones （populated areas）. A 120 kin： area was selected, this include Parral City and its surroundings. From this area 30 samples were obtained. For this purpose, Atomic Absorption Spectroscopy technique was used, expecting high concentrations of heavy metals, above the permit limits, since several studies carried out in the same region, as in San Francisco del Oro Chihuahua, show that the concentrations of all the elements sampled, in topsoil, were above the limits. The analysis in the space distribution of the heavy metal detected will allow us to set the points with the highest susceptibility to the accumulation of those pollutants and to propose mitigation measures and control.

Estimate of the Crystallization Kinetics in Stoichiometry Compositions Films of Ge:Sb:Te

The aim of this work is to compare the isothermal crystallization kinetic in the films along GeTe-Sb2Te3 line with composition Ge2Sb2Te5, Ge1Sb2Te4 Ge1Sb4Te7 and Ge4Sb1Te5 using mainly Johnson–Mehl–Avrami-Kolmogorov (JMAK) model. Results obtained have shown different crystallization mechanism in the investigated films. In Ge2Sb2Te5 and Ge1Sb2Te4 films the analysis of the kinetic results (Avrani coefficient) showed that at the beginning of crystallization a metastable phase appeared with the Ge1Sb4Te7 composition, this is followed by the nucleation and growth of the stable fcc phase up to full crystallization. In contrast Ge4Sb1Te5 and Ge1Sb4Te7 films show diffusion control growing from small dimension grains with decreasing nucleation rate.

Consolidation of AA 7075-2 wt% ZrO2 Composite Powders by Severe Plastic Deformation via ECAP

The powders of the AA 7075-ZRO2 were mixed by mechanical milling, but it was found that the system presents a few disadvantages when processed by conventional sintering and hot extrusion, since intermetallic phases between ZrO2 particles and alloying elements were formed. Equal channel angular pressing （ECAP） processing was proposed as an alternative method to consolidate the composite where there is no intermetallic formation. The analysis of the ECAP process showed that the intermediate temperature （220℃） produced a higher consolidation level than conventional sintering and hot extrusion （400 and 500℃, respectively）. This fact was supported by relative density analysis. In the case of the sintered and hot-extruded sample, the relative density exhibited a value of 0.95, while ECAP sample showed a value of 0.98. Hardness values show that microstructural refinement obtained during mechanical milling was preserved during ECAP processing even when it was carded out at 220℃.